Method and apparatus for straightening tubular members



y 1966 R. F. DOLAN ETAL 3,253,444

METHOD AND APPARATUS FOR STRAIGHTENING TUBULAR MEMBERS Filed July 11,1963 INVENTOR.

% gaff ATTORNEY United States Patent 3,253,444 METHOD AND APPARATUS FORSTRAIGHTEN- ENG TUBULAR MEMBERS Richard F. Dolan, Mount Clemens, andFrederick B. Hill, Utica, Mich, assignors to General Motors Corporation,Detroit, Mich, a corporation of Delaware Filed July 11, 1963, Ser. No.294,279 Claims. (Cl. 72-107) This invention relates to a method andapparatus for straightening metal tubes.

In the design, manufacture and operation of many devices it is necessaryto have a metal tubular member which is as nearly as possible concentricabout its longitudinal axis. Typical of such devices is a motor vehiclewhich has a propeller shaft or driveshaft constructed of a tubularmember with universal joints at opposite ends. In such an instance, itis desirable to have the tubular driveshaft as nearly concentric aboutthe longitudinal axis as possible to provide true running, proper[balancing and little vibration.

Such shafts are formed from standard tube stock which must bestraightened before it can be used. In the past it has been common touse contoured rollers traversing the tubular stock to straighten thetube relative to its longitudinal axis. The rolls are generally powerdriven to drive the tube past the rollers and the process requiresbending and reverse bending of the tube about its axis with rotation ofthe tube as the bending occurs. The commonly employed method is slow andrequires skilled and experienced operators to properly straighten thetube. Generally speaking, a large mechanical or hydraulic ram isrequired to [bend the tube and it is necessary to continue the processintermittently, measuring the eccentricity and concentricity followingeach ibending operation. With devices of this nature it is not possibleto straighten the end sections of the tube, portions which may beparticularly important in vehicle propeller shafts to prevent adisproportionate section of unbalance.

The method and device in which this invention is embodied comprises,generally, a machine for rotating the tubular member on its longitudinalaxis and a plurality of rollers. disposed circumferentially about thetube and equidistant from the tube axis. The rolls are generallyH-shaped in longitudinal cross-section to provide two point contact withthe tubular member. As the rolls traverse the length of the tube theylocally deform the surface of the tube beyond its elastic limit and movethe surface into the proper relationship with the centerline of thepropeller shaft. The surf-ace material is actually displaced toestablish a centerline coincident with the axis of rotation of thetubular member.

This method and apparatus avoids most of the disadvantages of thepresently known tube straightening equipment. With apparatus of thisnature the workpiece is rotated rather than the roller members and theroller members are thus free to turn at will to provide the propermaterial movement. Straightening the tubular member is accomplished byplastic deformation of the metal in the area of contact between the tubeand the roll in those parts of the tube that are eccentric relative tothe tube axis.

These and other advantages Will become more apparent from the followingdescription and drawing, in which:

FIGURE 1 is a perspectiveview of a machine capable of performing themethod and showing the relative position of the various parts of theapparatus;

FIGURE 2 is a cross-sectional view of a portion of the apparatusillustrated in FIGURE 1, taken substantially along the line 22 of FIGURE1, and looking in the direction of the arrows to show the tubular memberand the disposition of the rollers thereabout;

3,253,444 Patented May 31, 1966 FIGURE 3 is a plan view of that portionof the apparatus shown in FIGURE 2, taken substantially along the line3-3 of FIGURE 2, and looking in the direction of the arrows; and

FIGURE 4 is a perspective view of a portion of a vehicle propeller shaftwhich has been straightened by the apparatus of FIGURES 1-3.

Referring more particularly to the drawing, FIGURE 1 best illustrates atypical machine and apparatus for accomplishing the method. A machineframe, illustrated generally by the numeral 10, carries a suitableelectric motor or other rotating device within the cabinet 12. The motorturns a typical chuck or the like 14 and may be controlled by a suitablecontrol panel 16.

At the opposite end of frame 10 is a tailstock assembly, illustratedgenerally by the numeral 18; and connecting the engine cabinet andtailstock assembly are a plurality of machine rails 20.

Disposed between the chuck 14 and the tailstock assembly 18 is a tubularmember, illustrated generally by the numeral 22, which, in the drawingfor illustrative purposes, is shown to be a vehicle propeller shafthaving universal joint halves 6, 8 secured to the respective endsthereof. One of the universal joint halves 6 on the one end of the shaftis mounted in chuck 14 and the other universal joint half 8 at theopposite end is received and rotatable in the tailstock assembly 18.Suitable adjustment means 24 for the tailstock 18 may be provided.

A carriage assembly, illustrated generally by the numeral 26, is mountedon rails 20 and contains the roller mounting cage 28. As will becomehereinafter more apparent, carriage 26 traverses along the rails 20 bythe action of the rollers on the tubular member so that the carriage 26need not be operated under power.

The roller supporting cage 28 may be formed in any suitable manner andis shown for illustration purposes in FIGURES 2 and 3 to comprise sidemembers 30 and 32. Disposed between the' side members are plates 34 towhich are adjustably secured the roller assemblies, illustratedgenerallyby the numeral 36. An open area in the side members 30 and 32,as shown in FIGURE 2 at the upper left portion, is provided so that thetubular member may be inserted therein.

Roller assemblies 36 are shown to include a mounting plate 38, sideplates 40 and rollers 42 which are rotatably secured in the side platesby pivot pins 44. It is important that the roller assemblies 36 beadjustable toward andaway from the tubular member 22 for purposes thatwill become hereinafter more apparent.

Any suitable adjustment means may be provided, and for purposes ofillustration the device shown in FIGURE 3 will be described. This deviceincludes a pair of dowel pins or locating pins 46 which are secured inthe mounting plate 38 and received in suitable apertures in the cagecross member 34. A threaded bolt 48 and locking nut 50 are received onthe cross members 34, the bolt 48 extending through the cross member 34to engage the mounting plate 38. Rotation of the bolt 48 will obviouslycause radial movement of the roller assembly 36 with respect to the'axistubular member 22.

As noted in FIGURES 2 and 3, the rollers 42 are of generally H shape intheir longitudinal cross-section, that is, the center portion 52 of theroller 42 is cylindrical, terminating in enlarged ends 54 which bearagainst the tubular member 22. The longitudinal axis 56 of each roll isangularly disposed or skewed with respect to the longitudinal axis 58.of the tubular member 22. The amount of skew or angular displacementmay be of any value but it has been determined that an angle ofapproximately 5 is most ellicient.

As noted in FIGURE 2, the four roller assemblies 42 are equally spacedabout the circumference of the tubular member 22 and the axis of eachroller 42 is equidistant from the tube centerline 58.

In operation the universal joint halves 6, 8 of the tubular member ordriveshaft 22 are secured in the machine by means of the chuck 14 andthe tailstock 18. The carriage 2 6 is disposed adjacent one end of thetubular memher and the rollers 42 are adjusted so that the flanges 54just engage the surface of the tube or shaft 22. Point contact isestablished between each flange of each roller and the tube. The chuck14 is then rotated and thus the propeller shaft along with it, and thecarriage 26 traverses the length of the propeller shaft 22 on the rails20. This is caused by the skew of the rollers 42 relative to the axis ofthe propeller shaft 22. As the flanges 54 of the rollers 42 traverse aneccentric portion of the tubular member, the surface is deformed beyondits elastic limit at the local portions of eccentricity. Finiteincrements of the tube surface are deformed and displaced to the properconcentric position about the established axis of rotation of the tube.Since there is point contact of the rolls with the surface of the tube,greater unit pressures may be applied to the tube than has beenheretofore possible with available straightening equipment. The rollsand carriage 26 traverse the length of the tube deforming and moving theeccentric portions of the tube surface and thus straightening the tube.At the end of the tube the direction of rotation may be reversed for asecond traverse of the length of the propeller shaft and additionaldeformation and realignment of the tube material.

FIGURE 4 illustrates a portion of a typical propeller shaft after themethod above described has been applied. As noted, a series of helicaldepressions 60 are formed, much the same as a thread formed on a bolt orthe like. The number of helical depressions is dependent upon the numberof roller flanges and more or less than eight as above described may befound tobe desirable.

Thus, a method and apparatus for straightening a tubular member isprovided which is more economical and efficient than presently availableequipment generally in use. The straightening process is through localplastic deformation and realignment of the material from which the tubeis made, to establish the proper centerline coincident with the axis ofrotation of the tubular member. The point contact provided by the rollsin traversing the length of the tubular member permits greater unitpressure or local pressures to be applied for the proper deformation andmovement of surface material.

What is claimed is:

1. A method of straightening a tubular driveshaft comprising the stepsof:

mounting the driveshaft for rotation about its axial centerline;

placing several pairs of rollers about said driveshaft such that eachroller has two point contact with said driveshaft, said rollers beingequidistant from the centerline of said driveshaft and having axes ofrotation angularly disposed with respect to said centerline;

and rotating said driveshaft to cause said rollers to traverse thelength thereof and to locally deform the surface of said driveshaftbeyond the elastic limit thereof and displace the eccentric portions ofsaid driveshaft, said angularly disposed axes of said rollers causingsaid rollers to be moved longitudinally along said driveshaft by contactwith and rotation of said driveshaft into concentricity with thecenterline of said driveshaft.

2. The method of straightening a tubular member having a longitudinalaxis comprising the steps of:

mounting the tubular member for rotation about said axis;

placing two pairs of rollers about said tubular member and in pointcontact engagement therewith, said rollers being equidistant from theaxis of said tubular member and movable inwardly toward said axis ofsaid tubular member and having axes angularly disposed relative to theaxis of said tubular member;

and rotating said tubular member to cause said rollers to traverse thelength thereof and to locally deform said tubular member beyond itselastic limit and displace the eccentric portions thereof intoconcentricity with the axis of said tubular member, said angularlydisposed axes of said rollers causing said rollers to be movedlongitudinally along said tubular member by contact with and rotation ofsaid tubular member.

3. The method of straightening a tubular member having a longitudinalaxis and concentric and eccentric portions relative .to said axis,comprising the steps of:

mounting the tubular member for rotation about said axis;

placing four rollers about said tubular member and equally spaced aboutthe circumference of said tubular member, each of said rollers beingsubstantially H-shaped in longitudinal cross-section to have two pointcontact with said tubular member, and said rollers having axesequidistant from the axis of said tubular member and angularly disposedwith respect thereto;

moving said rollers radially inwardly toward the axis of said tubularmember a distance adequate to deform the eccentric portions of saidtubular member;

and rotating said tubular member to cause said rollers to traverse thelength thereof and to locally deform the eccentric portions of saidtubular member beyond the elastic limit thereof into concentricity withthe axis of said tubular member, said angularly disposed axes of saidrollers causing said rollers to be moved longitudinally along saidtubular member by contact with and rotation of said tubular member.

4. Apparatus for straightening a tubular member having a longitudinalaxis comprising:

means for mounting and rotating said tubular member about .said axis; aplurality of rollers disposed circumferentially about said tubularmember and equidistant from said axis, said rollers being substantiallyH-shaped in longitudinal cross-section to have two point contact withsaid tubular member, said rollers having axes angularly disposedrelative to said axis of said tubular member and being movable radiallyinwardly toward said axis of said tubular member, said angularlydisposed axes of said roller causing said rollers to be movedlongitudinally along said tubular member by contact with and rotation ofsaid tubular member; whereby said rollers traverse the length of saidtubular member upon rotation thereof and locally deform eccentricportions of said tubular member beyond the elastic limit thereof andinto concentricity with said axis of said tubular member. 5. A method ofstraightening a drive shaft assembly having a tubular driveshaft memberand a universal joint member secured to each end of said tubular member,whereby the axis of said tubular member is to be made concentric withthe axis of said end members, comprising the steps of:

mounting the driveshaft assembly for rotation about the axial center ofrotation of said end members;

placing a plurality of rollers circumferentially disposed equidistancefrom the center of rotation of said end members at one end of saidtubular member, said rollers having axes angularly disposed from thecenter of rotation;

moving said rollers radially inwardly toward the axial center ofrotation of said end member a distance ade- 5 6 quate to deform theeccentric portions of said drive- References Cited by the Examiner d hft b1 UNITED STATES PATENTS rotating sa1 rives a assem y; 1 E 7 33 I andmoving said rollers longitudinally along the length 313 gggggz z of saidtubular member, said angularly disposed axes 5 2:991:67Q 7/1961 Meyer ofsaid rollers causing said rollers to be moved lon- 3,137,926 6/1964Barlow gitudinally along said tubular members by such rotation and bycontact with said tubular member, and FOREIGN PATENTS locally deformingthe eccentric portions of said drive- 10 34,713 10/1394 yshaft beyondthe elastic limit thereof and aligning I the axis of said drive shaftwith the axis of said end CHARLES LANHAM Pr'mary Exammer' member. H. D.HOINKES, Assistant Examiner.

1. A METHOD OF STRAIGHTENING A TUBULAR DRIVESHAFT COMPRISING THE STEPSOF: MOUNTING THE DRIVESHAFT FOR ROTATION ABOUT ITS AXIAL CENTERLINE;PLACING SEVERAL PAIRS OF ROLLERS ABOUT SAID DRIVESHAFT SUCH THAT EACHROLLER HAS TWO POINT CONTACT WITH SAID DRIVESHAFT, SAID ROLLERS BEINGEQUIDISTANT FROM THE CENTERLINE OF SAID DRIVESHAFT AND HAVING AXES OFROTATION ANGULARLY DISPOSED WITH RESPECT TO SAID CENTERLINE; ANDROTATING SAID DRIVESHAFT TO CAUSE SAID ROLLERS TO TRAVERSE THE LENGTHTHEREOF AND TO LOCALLY DEFORM THE SURFACE OF SAID DRIVESHAFT BEYOND THEELASTIC LIMIT THEREOF AND DISPLACE THE ECCENTRIC PORTIONS OF SAIDDRIVESHAFT, AND ANGULARLY DISPOSED AXES OF SAID ROLLERS CAUSING SAIDROLLERS TO BE MOVED LONGITUDINALLY ALONG SAID DRIVESHAFT INTOCONCENTRICITY WITH AN ROTATION OF SAID DRIVESHAFT INTO CONCENTRICITYWITH THE CENTERLINE OF SAID DRIVESHAFT.